Hassaan is derived from Arabic word 'Haseen' and Ahmed mean 'Much praised' in Urdu; so
literally Hassaan Ahmed means a highly praised
beautiful person.
Hassaan was also a tribal leader of Hassassins (Highly trained assassins in ancient times in the era of Fatimid Empire of Persia and Seyria who use sordid means of medications and trances to train their assassins; in short they were ruthless killers or highly skilled mindless murderers)
Hassaan-i-sabbah was a Man of high
intellect, therefore he introduced a new form of torture...he believed that physical pain is temporary so he use to bereft one from his fortitude and inflict irreversible damage to ones mind n soul.
From the legend Hassaan is also believed to be a person who is very dangerous and merciless.
like its said 'Different people, different mentality.'
So You cannot define Hassaan Ahmed, I just gave some facts :)